1. Field of the Invention
This present invention relates to the field of controlled actuation mechanisms. In particular, the present invention relates to the application of controlled magnetic forces as a means of actuating and positioning objects of interest.
2. Background Art
That certain xe2x80x9cstonesxe2x80x9d would attract bits of iron has been well known for centuries. Such materials that have such metal attracting properties are called magnets. A magnet is said to have what is known as magnetic lines of force, invisible to the naked eye but measurable none the less. These lines of force radiate from each end of a bar magnet. Each end is said to be polarized, one being a north (N) pole and the other a south (S) pole. The strength of this magnetic field is dependent on the strength of the magnet. This type of magnet is sometimes called a permanent magnet.
In 1820 Oersted discovered that a current in a wire can also produce magnetic effects, namely, that such current could change the orientation of a compass needle. The magnetic effect of the current through a wire can be intensified by forming the wire into a coil with many turns. The space around the magnet or current carrying wire is defined as the site of a magnetic field. The magnetic effect of current flowing through a coil can be further intensified by providing an iron core inside the coil.
Magnetic actuators take advantage of magnetic effects. Magnetic actuators appear in many forms, including relays, motors, automatic valves, and the like. Magnetic actuation offers the possibility of generating repulsive forces in addition to attractive forces, increasing the flexibility of magnetic actuators.
Current controlled magnetic fields may be used for actuation or positioning of objects. One example is the stepper motor. A stepper motor is an electromechanical device which converts electrical pulses into discrete mechanical movements. The shaft or spindle of a stepper motor rotates in discrete step increments when electrical command pulses are applied in the proper sequence. Motor rotation has several direct relationships to these applied input pulses. The sequence of the applied pulses is directly related to the direction of the motor shaft rotation. The speed of motor shaft rotation is related to the frequency of the input pulses and the length of rotation is directly related to the number of input pulses applied.
One problem with stepper motors is that they provide only one-dimensional rotational positioning due to their cylindrical construction. Many applications require two or three dimensions of rotation. These applications include aiming, such as for cameras, microphones, light sources, and the like. Other applications include positioning devices in space, such as robotic manipulators, probes, and the like. What is needed is to supply multiple degrees of rotation with a single actuator.
The present invention uses magnetic forces as a controlled actuation mechanism to move and position certain objects of interest.
A magnetic actuation system is provided. The system has a first spherical surface with at least one magnetic positioner attached. A second spherical surface is positioned to move relative to the first spherical surface. A plurality of controlled electromagnets are spaced about the second spherical surface. Control logic energizes at least one of the controlled electromagnets to create magnetic interaction with at least one magnetic positioner to move the first spherical surface relative to the second spherical surface.
In various embodiments of the present invention, each magnetic positioner may be a permanent magnet, an electromagnet, magnetically attracted material, or the like. The spherical surfaces may be concave or convex. Either or both spherical surface may include a flexible printed circuit.
In yet another embodiment of the present invention, a device to be aimed, such as a camera, may be attached to either of the spherical surfaces.
In still another embodiment of the present invention, the spherical surfaces may form a joint for positioning a device such as a robotic manipulator.
In a further embodiment of the present invention, the control logic receives signals from the plurality of controlled electromagnets. Each signal received from one of the controlled electromagnets is generated in response to at least one magnetic positioner moving past the controlled electromagnet. The control logic may use these signals to learn a trajectory of the first spherical surface relative to the second spherical surface.
A method of magnetic actuation for aiming an object is also provided. The object is affixed to a curved surface. The curved surface has at least one attached magnetic positioner. The curved surface is placed in proximity to a second surface. The curved surface is capable of moving in at least two rotational degrees of freedom relative to the second surface. The second surface has a plurality of individually controlled electromagnets arranged in a grid. At least one of the controlled electromagnets is energized to rotatively move the curved surface relative to the second surface to aim the object.
A magnetically aimed camera is also provided. The camera includes a housing having a curved surface and an aperture surface, the aperture surface defining an aperture. An imaging array is disposed within the housing. The imaging array receives light through the aperture. At least one magnetic positioner is disposed within the housing at the curved surface. A socket receives the housing such that the housing curved surface rotates within the socket. A plurality of controlled electromagnets are disposed within the socket for rotating the housing.
In various embodiments of the present invention, control logic operates the aimed camera to implement at least one of vergence movements, vestibulo-ocular movements, optokinetic movements, saccadic movements, and pursuit movements.
A magnetically aimed transducer is also provided. A housing holds the transducer. At least one magnetic positioner is disposed within the housing at a curved surface. A socket receives the housing with the housing curved surface rotating within the socket. The housing is positioned in the socket such that the transducer is aimable through an opening in the socket. A plurality of controlled electromagnets are disposed within the socket. Each controlled electromagnet is controllable to magnetically interact with the at least one magnetic positioner to rotate the housing within the socket, thereby aiming the transducer.
The above objects and other objects, features, and advantages of the present invention are readily apparent from the following detailed description of the best mode for carrying out the invention when taken in connection with the accompanying drawings.